Methods and kits for transferases

A method for detecting transferase activity of a sample includes contacting the sample with a substrate and at least one of a phosphate group donor and a phosphate group acceptor. The substrate includes a reporter compound and amino acids. A peptidase is added that cleaves a non-phosphorylated substrate at a first rate and a phosphorylated substrate and a second rate. The output of the reporter compound is detected. In a preferred embodiment, the transferase activity detected is a kinase activity. In another preferred embodiment, the transferase activity detected is a phosphatase activity. Also provided is a method of screening for alterations in a transferase reaction. Kits and peptide substrate are also provided for carrying out at least one of the methods of the invention.